Guide on Adjusting Soil pH After Sowing: Techniques for Lowering Alkalinity

Acidifying soil is essential for plants that thrive in low pH conditions, such as azaleas, blueberries, and rhododendrons. Here's a guide to help you understand the various soil amendments available and how to use them effectively.

Firstly, it's crucial to follow the manufacturer's instructions when using iron sulfate to avoid harming plants. Iron sulfate provides faster results compared to sulfur, but requires a larger volume of product. Sulfur, along with iron sulfate, coffee grounds, compost, mulch, vinegar, lemon juice, peat moss, aluminium sulfate, ammonium sulfate, and ferrous sulfate can be used to acidify soil.

Ammonium sulfate and sulfate of ammonia are examples of ammonia-based fertilizers that can acidify soil. These ammonium-based fertilizers have the greatest potential to acidify soil compared to other nitrogen fertilizers.

If you're using coffee grounds in your compost bin or pile, a good ratio to maintain is three parts leaves to one part fresh grass clippings to one part coffee grounds by volume. When using coffee grounds as a soil amendment, work them into the soil to a depth of 0.5 to 4 inches. However, the composition of the compost pile should not exceed 20% coffee grounds by volume, or it can be toxic to plants.

To make your compost more acidic, use high-acid organic matter such as oak leaves, pine needles, coffee grounds, citrus fruits, and fruit waste. Regularly test the pH of your compost with pH testing strips or devices to ensure it remains acidic.

Soil can be tested for pH level by sending a sample to a professional lab or using a home testing kit. It is recommended to test the soil before planting to determine the types and amounts of soil amendments required. If the soil pH is 7.0 or lower, it's already acidic, but may need further acidification for ericaceous plants.

Elemental sulfur can be used to break up clay soil and lower its pH level. Sulfur takes a long time to lower the pH of the soil, possibly a few months or longer. On the other hand, aluminium sulfate acts faster but is costlier. The price-performance ratio of soil acidifiers like sulfur, aluminum sulfate, and iron sulfate varies, with elemental sulfur being cost-effective but slower acting.

Spread a 1-2 inch (2.5-5 cm) layer of garden soil over the compost pile to help the microorganisms in the soil boost the decomposition process. If used as a mulch on top of the soil, a layer of leaves or bark mulch will help keep the grounds from drying out and repelling water.

Remember, it's important to avoid adding too much deciduous leaf and cuttings, as these tend to be more alkaline. Also, do not add lime, calcium carbonate, or other materials rich in calcium, as these are alkaline.

Lastly, when using iron sulfate, it is recommended for acidifying soil after planting and for treating iron chlorosis.

By following these guidelines, you can ensure that your soil is properly acidified for your acid-loving plants, promoting healthy growth and vibrant blooms.